1. Field of the Invention
This invention relates to a method of and an apparatus for fractionating components in liquid chromatography (hereinafter abbreviated as LC).
2. Description of the Prior Art
In general, the LC is a method of separating various components in a sample by applying the sample into a separation column while causing an eluent (or eluate) to flow continuously into the column. Usually, a detector for optically detecting each separated component is disposed on the column outlet side, and a recorder is connected to the detector. Each component detected in the detector is electrically measured in a photoelectric tube or the like to produce electric indication, which is transmitted to the recorder to be recorded continuously as a graph on a chart paper in the recorder.
When fractionating components separated in the conventional LC for the purposes of other tests or the like, the eluent from the detector is led to an apparatus so called fraction collector to obtain solution containing the separated components in a test tube of the collector.
When separating a small amount of component in a small volume of sample, capillary column liquid chromatography (hereinafter abbreviated as CCLC) is used particularly. However, the volume of solution containing a component separated and obtained by the CCLC is very small, for instance 1 to 10 .mu.l, and it is difficult and almost impossible to reliably fractionate such a small amount of liquid into a test tube of the fraction collector used in the conventional LC. Besides, the amount of liquid corresponding to one peak on the chromatogram is very small, and by causing the liquid to be dropped as drops into the test tube for fractionation, the detected component that is condensed in the column chromatography is diluted.
As a method for solving this problem, the inventor has earlier invented a "Method of Blotting Components in Capillary Column Liquid Chromatography" (disclosed in Japanese Laid-Open Patent Publication No. 5-264532). This disclosed invention features that an eluent containing detected components led out from the column, is successively adsorbed onto an adsorbing sheet disposed in a chromatogram. More specifically, instead of dropping the eluent from a chromatography flow path end, the eluent is continuously blotted onto the adsorbing sheet. The necessary portions of the resultant adsorbing sheet are cut out and preserved to permit very small amounts of detected components to be extracted faithfully to the detected component separation status.
In this method, however, the eluent is blotted on the adsorbing sheet. This means that it is necessary to extract the component from the adsorbing sheet in a subsequent treatment. Therefore, there arise problems in the man-hour of the extracting operation and the efficiency of the extraction. In addition, a technique is needed to obtain efficient adsorption of the component on the adsorbing sheet. The method, therefore, is not always convenient for the subsequent treatment. Further, when the spots of components are close to one another, it is sometimes difficult to select the cutting positions of the adsorbing sheet.